Efficient Cd-Free Flexible CZTSSe Solar Cells with Quality Interfaces by Using the Zn_1–xSn_xO Buffer Layer

Abstract

The severe carrier recombination at the CZTSSe/CdS heterojunction interface and high toxicity of Cd limit the further development of flexible Cu 2 ZnSn(S, Se) 4 (CZTSSe) solar cells. Here, we apply a suitable and environmentally friendly Zn 1−x Sn x O (ZTO) buffer layer to suppress the interface recombination in the flexible solar cell for the first time. The ZTO buffer layers with good qualities have been successfully obtained by varying the Sn/(Zn + Sn) value. The solar cell has obtained an efficiency of 8.7%, which is the highest efficiency reported for a Cd-free flexible CZTSSe solar cell so far. The optimal device has more ideal diode parameter values, indicating that the interface quality is significantly improved. The V OC -T characteristic demonstrates that the interfacial recombination of flexible ZTO devices has been greatly reduced. The theoretical simulations show that the flexible CZTSSe devices with optimal ZTO layers achieve good band alignment to reduce the interface recombination, elucidating the intrinsic link between the band structure and the device performance. This investigation provides a solution to achieve environmentally friendly and efficient flexible CZTSSe solar cells by designing the interface engineering of the absorber/buffer heterojunction in solar cells.

Inorganic Thin-Film Solar Cells: Challenges at the Terawatt-Scale

“…As mentioned above, in the case of CZTSSe, appropriate absorber material processing plays a crucial role in improving the device efficiency: each absorber material requires specific material processing to control the grain growth, elemental composition, and defect properties [119][120][121]. In Table 6, an overview of recent studies on the development of Sb 2 (S,Se) 3 solar cells is given.…”

Efficient Environmentally Friendly Flexible CZTSSe/ZnO Solar Cells by Optimizing ZnO Buffer Layers

“…Cu 2 ZnSn(S,Se) 4 (CZTSSe) is one of the most promising absorber materials for thin-film solar cells due to its earth-abundant, non-toxic constituent elements and tunable bandgap [ 1 , 2 , 3 , 4 , 5 , 6 ]. The maximum power conversion efficiency ( PCE ) of CZTSSe solar cells can reach 13.0% [ 7 ] and 11.2% [ 8 ] on rigid substrates and flexible substrates, respectively.…”

Synergistic effects of Li&Na co-doping enabling flexible Cu2ZnSn(S,Se)4 solar cells with over 10% certified efficiency

“…Lightweight and exible thin-lm solar cells show great potential applications in weight-restriction places, curved surfaces, wearable and portable electronics, solar powered autos and so on [1][2][3][4][5] . Cu 2 ZnSn(S,Se) 4 (CZTSSe) has become a great potential thin-lm absorber material due to its low cost, earthabundant and environmental elemental components and stable structure [6][7][8][9] . Recently, the power conversion e ciency (PCE) of the best exible CZTSSe solar cell has exceeded 11% 10 , but which is much lower than that (20.8%) of its predecessor, the exible CIGS solar cell 11 .…”